This invention relates generally to the field of devices utilized in surgery to retract and retain tissue, organs or the like to provide the surgeon with access or an unobstructed pathway to an organ, bone, tissue or point in the body. Such devices are typically referred to generically as retractors. More particularly, the invention relates to retractors utilized with minimally invasive surgical techniques, wherein minimally sized openings are created in the body rather than relatively large incisions. Tubular devices known as cannula retractors, or spreading retractors having finger-like extensions or blades, are inserted into the small opening and through or around the body tissues, muscles, tendons, ligaments, etc., thereby minimizing damage to the body. The surgeon then performs the necessary procedure through the retractor tube using specially designed tools and equipment.
A problem with known retractors used in minimally invasive surgery is that the distal end profile or configuration of the device is fixed. A typical tubular retractor has a circular or elliptical transverse cross-section with the distal end lying in the plane perpendicular or slanted relative to the longitudinal axis. Other tubular distractors may have non-planar ends of varying configurations, such as having a spatula-like extension. Spreading retractors likewise have varying end configurations. Because the distal end configurations of the devices are fixed, the devices often fail to prevent creep or herniation of tissue at or around the distal end of the device, and this tissue creep can interfere with the necessary physical or visual access. This is particularly true when the distal end of the retractor device is positioned adjacent or near a bone, such as a vertebra for example, that does not have a planar or smooth outer contour, or where the retractor device is disposed at a non-perpendicular angle to the bone. In these circumstances it often becomes necessary for the surgeon to cut away the interfering tissue, thereby creating additional tissue damage that needs to heal and increasing the possibility of detrimental results such as bleeding, increased pain, infection and the like.
One attempted solution that is found in certain retractors of the spreadable blade type is to provide shim members that are mounted in interior channels disposed in each of the blades. The shim can be extended beyond the distal end of the blade by sliding the shim relative to the blade. The shortcomings of this solution to the problem of tissue creep is that the location of the shims are determined by the location of the blades after they have been positioned and spread. Thus, the surgeon cannot address the problem of tissue creep that occurs between the blades.
The invention at hand addresses this tissue creep problem by providing a retractor device for minimally invasive surgery that incorporates extension members in the form of shields or barriers that are selectively attached at, adjacent or to the end of a tubular retractor, and to the ends or sides of blade-type spreadable retractors, so as to extend therefrom in order to fill any gaps between the distal end or side of the retractor and the bone, organ or other body component of concern, such that tissue is precluded from creeping or herniating into the gap. The extensions may be mounted to the retractor at any point about or adjacent the distal end utilizing various mechanical joining techniques, and the extensions may vary in shape, size, thickness and other characteristics. The extensions may be preformed with a fixed curvature so as to match the interior curvature of the retractor, or they may be composed of a flexible material such that they adapt to the interior curvature of the retractor upon affixation. The extensions may be provided with teeth, apertures, slits or the like to better prevent tissue creep.
Specialized applicator equipment or tools are preferably provided that allow the surgeon to grasp or secure a particular extension, to insert the extension into and down the retractor, and to affix the extension to the interior wall or distal end of the retractor. Such equipment may take the form of forceps that retain the extension member during insertion and placement within the tubular retractor or other retractor blade.